1. Field of Invention
This invention relates to the art of clutches, and more specifically clutches incorporating brakes, especially as related to lawn care devices.
2. Description of the Related Art
Clutch brake mechanisms are well known in the art of lawn care equipment to be used to engage and disengage a pulley xe2x80x94such as a pulley used to drive (usually rotate) one or more cutting blades. Typically such clutches include a shaft rotatably actuated by a prime mover, such as an engine working through a pulley-belt system or other power transferring device. The shaft usually includes a disk, sometimes referred to as a clutch plate, having an aperture fashioned within the center within which is received the shaft. The disk is connected so that it rotates with the shaft. A friction material or pad may be adhered or fastened to one or both faces of the clutch plate. A second item, usually a pulley, is disposed in proximity to the clutch plate for selective engagement therewith. While the clutch plate is engaged with the pulley, rotational power is transferred from the clutch plate to the pulley, which may be operatively connected to a subsequent device (such as a mower deck having one or more blades for cutting vegetation). Upon disengaging the clutch plate from the pulley, a braking mechanism may be incorporated that arrests the motion of the pulley.
Typically such clutches are of two general typesxe2x80x94electric clutches and mechanical clutches. Both types are useful for their intended purpose. However, both types also have problems. Common problems with electric clutches include the fact that that they are relatively expensive and that they may create a sudden, strong shock when they are activated. Such shocks may reduce the life of some lawn care equipment components. Common problems with mechanical clutches include the number and weight of components required to form the clutch/braking mechanism. Often belt keepers, pivoting idler pulleys and other components are necessary.
One clutch/brake assembly is described in U.S. Pat. No. 5,570,765 to Patridge. Partridge discloses a clutch/brake assembly for a machine having a rotating output shaft and a fixed mounting plate which includes an input disc, an output disc having a high friction pad and a brake member. A cam assembly is provided to be coupled with the input disc and moveable between first and second positions. Partridge further discloses that upon movement of the cam assembly from a second position to a first position, the input disc is moved out of engagement with the high friction pad and into engagement with the brake member.
Another clutch/brake device is described in U.S. Pat. No. 5,033,595 to Pardee. Pardee discloses a clutch/brake unit having a braking element that applies a brake and disengages a clutch when shifted axially in response to turning of a rotary actuator in one direction. The patent further discloses that the braking element includes balls and grooves formed in a flange so that the braking element is shifted downward by rotation of an actuator and the camming action of the balls.
What is needed is a mechanical clutch-brake that reduces the number of parts that make up the clutch-brake mechanism. By simplifying the construct of the assembly both the manufacturing and repairing of the unit is simplified, saving time and material cost.
One objective of the present invention is to provide clutch-brake assembly having an actuating means operatively connected to the brake member, also referred to as the brake ring, and the lever for applying a displacement force relative only to the brake member and the lever.
It is yet another object of the present invention to provide a clutch-brake assembly actuated by a vacuum actuator.
It is still yet another object of the present invention to provide a clutch-brake assembly having a brake member pivotally connected to a housing member.
According to the present invention there is provided a clutch-brake assembly having a concave housing member, a shaft operatively connected thereto and a clutch plate operatively received onto the shaft for rotation therewith. Leaf springs are attached at one end to a shoulder of the shaft and at a second end to the clutch plate so as communicate rotational power thereto. Additionally the leaf springs facilitate axial displacement of the clutch plate by allowing deflection so that upon displacement of the clutch plate a friction pad, adhered to the lower surface of the clutch plate, may operatively engage a pulley member transferring rotational power from the shaft to the pulley member. A annular brake member or brake ring is included that is pivotally connected at one point along the ring with respect to the housing member. At the opposite side of the brake ring with respect to the pivotal connecting point, a braking friction pad is adhered thereto. Springs bias the brake ring into braking engagement with the pulley member.